Dental material based on alkoxysilyl-functional polyethers containing a salt of a strong acid as catalyst

ABSTRACT

The present invention relates to condensation-cross-linking dental materials, especially condensation-cross-linking two-component dental materials, on the basis of alkoxysilyl-functional polyethers containing at least one alkoxysilyl-functional polyether as well as at least one catalyst, wherein the at least one catalyst is a salt formed from a weak organic base whose PK BH+  value measured in water is between −1 and 7 and at least one strong acid whose pKs value measured in water is lower than 2 and which preferably has a structure that permits mesomeric stabilization of the negative charge after deprotonation of the acid.

The present invention relates to condensation-cross-linking dentalmaterials, especially condensation-cross-linking two-component dentalimpression materials, based on alkoxysilyl-functional polyethers, whichare suitable in particular for taking impressions, and to use of same.Such materials are used in dental medicine for purposes such as takingteeth impressions, bite registration, relining dental prostheses,temporary and permanent dental cement, temporary sealing material ordental duplicating material.

Known condensation-cross-linking dental materials usually containhydroxyl-functional polymers with a silicone backbone, which cure in thepresence of organotin compounds as catalysts, alkoxysilanes and/orsilicic acid esters as cross-linking agents and water. However, suchmaterials are relatively hydrophobic because of the silicone backbone ofthe polymer, and so considerable quantities of surfactants must be addedto them in order to lower the surface tension and to adjust thenecessary wettability. A further disadvantage of these compositions liesin the use of toxicologically questionable tin compounds as catalyst.

As alternatives thereto there are known two-component dental materials,which contain polymers having terminal alkoxysilyl groups and ahydrophilic polyether backbone, and which exhibit sufficientlyhydrophilic properties for wetting the moist tooth substance. Usuallythese materials are composed of a base component containingalkoxysilyl-functional polyethers that have an average molecular weightof 800 to 20,000 g/mol and that can also contain urea and/or urethanegroups depending on the synthesis, fillers and possibly other additives,and of a catalyst component which, besides fillers and possibly otherauxiliary substances, contains an organic and/or inorganic acid ascatalyst.

From European Patent 0269819 B1 there are knowncondensation-cross-linking two-component dental materials whose basecomponents contain polyaddition products containing alkoxysilyl endgroups and having a predominantly linear molecular structure and anaverage molecular weight of 800 to 20,000 g/mol, which have a content ofpolyether groups of 25 to 90 wt %, a content of urethane groups of 0.5to 10 wt %, a content of urea groups of 0.5 to 10 wt % and a content ofterminal alkoxysilyl groups of 1 to 25 wt %, and whose catalystcomponents have a mixture containing water as well as organic and/orinorganic acids in weight ratios (water/acid) of 1:0.01 to 1:40.However, the synthesis of the base component containing functionalpolyether polymers is very complex and expensive. A further disadvantageof these dental materials lies in the use of acid-containing catalysts.Firstly, the acid catalysts can harm the oral mucosa and the enamel byacid etching during molding in the patient's mouth. In addition, thesesystems do not permit any addition of nitrogen-base-containingsubstances, such as astringents, for example epinephrine, or otheracid-labile therapeutic additives, since these are inactivated by theacid catalyst due to protonation or cleavage. Furthermore, the use ofacids in production of the dental materials necessitates appropriatesafety precautions.

European Patent 1226808 A2 discloses condensation-cross-linkingtwo-component dental materials composed of a base component and catalystcomponent, the base component of which contains alkoxysilyl-functionalpolyethers with linear or branched main chain and an average molecularweight of 800 to 20,000 g/mol, which have a content of polyether groupsfrom 20 to 95 wt %, a content of terminal alkoxysilyl groups from 0.2 to25 wt % and possibly a content of urethane groups or urea groups of upto 10 wt %, and whose catalyst components have a mixture containingwater as well as organic and/or inorganic acids in weight ratios of1:0.01 to 1:40. Preferably the catalyst component containsp-toluenesulfonic acid as catalyst as well as a polyether diol andfurther additives, such as fillers, paraffin, emulsifier and the like.Certainly the functional polyether polymers used in these dentalmaterials can be synthesized more easily and cheaply than those citedhereinabove, and they are characterized by better setting kinetics.However, these dental materials also make use of acid-containingcatalysts, so that on the one hand the risk of harm to the oral mucosaas well as the enamel exists during molding in the patient's mouth and,moreover, no acid-labile therapeutic additives can be mixed in withthese materials. A further disadvantage of the systems lies in theirpoor storage stability. However, a setting time that is constantregardless of storage time is one of the most important requirements ofa dental impression material.

In International Patent WO 99/18912, the use of metalloorganic compoundssuch as iron or tin compounds, for example tin(II) octate, or oftertiary amines such as triethylamine, is proposed for cross-linking ofpolyurethanes to be used as adhesives or sealants and containingpolyether groups. A disadvantage of these catalysts, however, lies intheir high toxicity, and so suitable safety precautions have to be takenin production of the materials, and use of the materials as dentalimpression compounds is not possible without further precautions. Inaddition, tertiary amines in particular are strong-smelling, and so theuse thereof in dental materials is not desirable. Furthermore, thepolyurethanes used in these materials are characterized by strongintermolecular interactions because of their high content of urethanegroups per molecule, and this, in view of the given chain length of themolecules, leads to higher viscosity of the materials compared withalkoxysilyl-functional polyethers, which have only two urethane groupsper molecule, and so only low contents of fillers can be used in thesematerials, in turn causing increased manufacturing costs.

Furthermore, from European Patent 1402873 A1 there is known atwo-component formulation, which sets at room temperature as anelastomeric material, and in which there is contained, in catalystcomponent B, an organic or inorganic acid and, in base component A, asilane-functionalized polyether derivative as well as a compound withantacid effect, the compound with antacid effect being chosen fromgroups composed of the basic or amphoteric oxides, hydroxides,carbonates, carboxylates and basic organic compounds with N, As, O, P, Sor Sb as the hetero atom as well as nitrogen-containing compounds withisocyanate, epoxide, carbodiimide or aziridine groups.

The object of the present invention is therefore to provide ahydrophilic condensation-cross-linking dental material, especially acondensation-cross-linking two-component dental impression material onthe basis of alkoxysilyl polyethers, which material is stable duringstorage, in particular has constant reaction kinetics even after atleast 18 months of storage time, has good biocompatibility, inparticular is neutral as to smell as well as taste, and containsconstituents that are toxicologically as safe as possible.

According to the invention, this object is achieved by acondensation-cross-linking dental material of the composition accordingto claim 1.

In connection with the present invention, it was surprisingly found thatthe salt catalysts to be used according to the invention have goodcatalytic activity for condensation reactions and are thereforeeminently suitable for being used as catalyst incondensation-cross-linking dental materials based onalkoxysilyl-functional polyethers. The inventive dental materials notonly have reaction kinetics that are suitable for dental materials butin particular also exhibit practical processing and setting times.Consequently, compared with substances known heretofore for thispurpose, such as metalloorganic compounds and tertiary amines, thesecatalysts are distinguished by good biocompatibility and are subject toless rigid safety precautions during preparation of the dentalmaterials. In particular, the use of heavy-metal catalysts, such asorganotin, organozinc or organolead catalyst compounds, can be dispensedwith. A further advantage of the salt catalysts used according to theinvention, especially compared with the primary, secondary and tertiaryamines known from the prior art, lies in their neutral smell and taste,which is an important property for a dental impression material, inorder to achieve acceptance by the patients and, for example, to avoidgagging reactions of the patients during application. In addition, itwas unexpected for the person skilled in the art that such dentalmaterials exhibit reaction kinetics that remain constant, especiallyconstant processing and setting times, even after several months ofstorage. This is due among other factors to the fact that, during thestorage period and after curing, the catalyst salts used according tothe invention do not enter into any side or degradation reactions withother constituents, such as the fillers, the polyethers that may be usedas paste-forming agents or the alkoxysilyl polyethers. Aside from this,compared with the use of a free acid and a free base, such as a tertiaryamine, the use of a salt as catalyst is also advantageous because thesalt has a relatively moderate pH, thus ensuring good compatibility ofthe inventive dental materials with the oral mucosa and with the enamel,meaning that no burning or irritation occurs during application.

The inventive dental materials can be formulated both as one-componentmaterial and as two-component material. Whereas the formulation of theone-component dental materials must be as absolutely anhydrous aspossible in order to prevent a reaction of the alkoxysilyl-functionalpolyethers during storage, and the reaction of the alkoxysilylpolyethers after application of the materials on the object from whichthe impression is to be taken is initiated by atmospheric moisture,water is preferably added to the catalyst component of the inventivetwo-component dental material. Preferably the two-component dentalmaterials are formulated such that

-   -   base component A contains        -   a) at least one alkoxysilyl-functional polyether,    -   and catalyst component B contains        -   b) at least one catalyst and        -   c) water,    -   the at least one catalyst b) being a salt formed from a weak        organic base whose PK_(BH+) value measured in water is between        −1 and 7 and at least one strong acid whose pKs value measured        in water is lower than 2.

According to a first special embodiment of the present invention, the atleast one catalyst is a salt formed from a weak organic base whosePK_(BH+) value measured in water is between −1 and 7 and at least onestrong acid whose pKs value measured in water is lower than 2, the acidhaving a structure that permits mesomeric stabilization of the negativecharge after deprotonation of the acid. Mesomeric stabilization as usedin the present invention means, in agreement with general textbookknowledge, that at least two limiting structures in which the negativecharge is localized on different atoms can be formulated for thedeprotonated acid, or that π electrons are delocalized in thedeprotonated acid, leading to stabilization of the deprotonated form.

Regardless of whether the inventive dental material is formulated as aone-component or two-component system, the catalyst salt used ispreferably formed from at least one acid whose pKs value measured inwater is smaller than 1 and particularly preferably smaller than orequal to 0.7 and/or at least one base whose PK_(BH+) value measured inwater is between 1 and 7, particularly preferably between 2 and 6 andquite particularly preferably between 3 and 6.

According to a further special embodiment of the present invention, theat least one catalyst salt is formed from an acid chosen from the groupcomprising p-toluenesulfonic acid, fluorosulfonic acid,trifluoromethanesulfonic acid, fluorosulfuric acid, 4-sulfophthalicacid, trichloroacetic acid, trifluoroacetic acid, benzenesulfonic acidand combinations thereof and/or from a base selected from the groupcomprising pyrrole derivatives, dimethylaniline, pyridine,2,4,6-N,N-pentamethylaniline, N,N-dimethylaniline, phenetedine,acridine, phenanthridine, quinoline, isoquinoline,2-amino-4,6-dimethylpyrazine, 4,6-dimethylpyridinamine, 3-methylpyridine(3-picoline), 4-phenylpyridine, 4-vinylpyridine, pyridazine,2-ethylpyridine, 2-butylpyridine, 1,7-phenanthroline, 2-aminopyrimidine,2-isopropylpyridine, 2-vinylpyridine, 2-N,N-dimethylaminopyridine,quinazoline, 4-chloropyridine, phenazine, 4-acetylpyridine, methylnicotinate, 3-benzoylpyridine, 2,2′-bipyridine, 2-phenylpyridine,2-tert-butylpyridine, pyrimidine, 3-iodopyridine, 3-fluoropyridine,3-chloropyridine, 3-bromopyridine, pyrazine, 7,8-benzoquinoline,2-chloropyridine, 4-cyanopyridine and combinations thereof. Particularlypreferably, there is used as catalyst a salt of p-toluenesulfonic acidwith pyridine or a salt of p-toluenesulfonic acid with2,4,6-N,N-pentamethylaniline.

In an improvement of the inventive idea, it is proposed that the cationsand/or acid anions provided in the catalyst salts to be used accordingto the invention contain alkoxysilyl groups. Thereby it is achieved thatthe catalyst salt is bound in the polyether matrix after curing of thedental material and can no longer be dissolved out of the dentalimpression material.

According to the invention, the dental materials can contain, ascatalyst, one or more of the aforesaid salts in any desired combinationwith one another. Preferably the dental material contains only one ofthe aforesaid salts as catalyst and, particularly preferably, no furthercatalysts, especially no metalloorganic metal salts, tertiary amines orfree acids, are used besides the one or more salts to be used accordingto the invention.

Preferably there is used in the inventive dental material a catalystsalt b) whose pH measured in water (Ampuwa, pH 5.8) is between 1 and 7,particularly preferably between 2 and 6 and quite particularlypreferably between 2 and 5.

As the person skilled in the art is aware, the quantity of catalyst saltto be used depends among other factors on the solubility of the salt inthe polyether matrix used. Preferably the quantity of catalyst salt tobe used, relative to the total mixture of the dental material, is 0.0005to 0.5 mmol/g, particularly preferably 0.0005 to 0.25 mmol/g and quiteparticularly preferably 0.0005 to 0.05 mmol/g. Obviously the catalystsalt used must have a minimum solubility in the polyether matrix used,in order to be able to act catalytically at all.

In order to keep the quantity of catalyst salt to be used as small aspossible, it is proposed in an improvement of the inventive idea that acatalyst salt with sufficiently high solubility in the polyethermaterial, or in other words with adequate catalytic activity, be used inthe dental material, the catalytic activity being characterized withinthe meaning of the present patent application by the curing timeaccording to ISO 4823 (1992 edition), determined by recovery afterdeformation. Preferably there is used a catalyst salt that, in apolyether matrix comprising as structural units polytetrahydrofuran,polyethylene glycol and particularly preferably polypropylene glycol aswell as mixtures and copolymers thereof, yields a curing time of lessthan or equal to 30 minutes, particularly preferably less than or equalto 15 minutes for a dental duplicating compound and a curing time ofless than or equal to 15 minutes, particularly preferably less than orequal to 10 minutes, quite particularly preferably less than or equal to7 minutes and most preferably less than or equal to 6 minutes for adental impression compound.

If the inventive dental material is formulated as a one-componentmaterial, it should be as absolutely anhydrous as possible, in order toavoid a reaction of the alkoxysilyl-functional polyether during storage.

In the case that the dental material is formulated as a two-componentmaterial, catalyst component B preferably contains water c), whereasbase component A is as absolutely anhydrous as possible. Preferablycatalyst component B of the inventive two-component dental materialcontains, relative to the total mixture, 0.005 to 3 mmol/g, particularlypreferably 0.01 to 2 mmol/g and quite particularly preferably 0.02 to 1mmol/g of water.

Preferably the inventive dental material contains at least onereinforcing filler d₁) and/or at least one non-reinforcing filler d₂).In formulation as a two-component material, base component A can containat least one of the aforesaid fillers, preferably at least onereinforcing filler and/or at least one non-reinforcing filler beingprovided both in base component A and in catalyst component B.

Suitable as reinforcing fillers d₁) are in particular highly disperse,active fillers with a BET surface of at least 50 m²/g and/or a primaryparticle size of smaller than or equal to 100 nm, particularlypreferably smaller than or equal to 80 nm. Particularly suitable arethose that have a primary particle size in the nanometer range and thatcan exist as aggregates and/or agglomerates. Preferably the at least onereinforcing filler d₁) is a substance selected from the group comprisingaluminum hydroxide, zinc oxide, titanium dioxide, zirconium dioxide andsilicon dioxide as well as precipitated and/or pyrogenic silicas.Obviously the aforesaid compounds can be used individually or in anydesired combinations with one another and, in fact, both in hydrophilicand in hydrophobed form.

Furthermore, the at least one reinforcing filler d₁) is present in theform of nanoparticles, as fibrous or flaky filler, such as mineral,fibrous filler, or as synthetic, fibrous filler.

As an improvement of the inventive idea, it is proposed that, informulation as two-component material, there be provided, preferably inbase component A, reinforcing fillers d₁) having a water content of atmost 0.5 wt %, particularly preferably of at most 0.3 wt %, quiteparticularly preferably of at most 0.15 wt % and most preferably beingabsolutely or substantially anhydrous, the water content beingdetermined by Karl Fischer titration.

According to a further special embodiment of the present invention, theat least one reinforcing filler d₁) with a BET surface of larger than 50m²/g in base component A has a pH of 4 to 11, preferably of 5 to 9 andparticularly preferably of 5.0 to 8.5.

In formulation as a two-component system, base component A preferablycontains, relative to component A, 0 to 50 wt %, particularly preferably0.1 to 40 wt % and quite particularly preferably 0.1 to 30 wt %, andcatalyst component B preferably contains, relative to component B, 0 to50 wt %, particularly preferably 0.1 to 40 wt % and quite particularlypreferably 0.1 to 30 wt % of at least one reinforcing filler d₁).

As non-reinforcing fillers d₂), the same substances as for reinforcingfillers b₁) are in principle suitable, although the non-reinforcingfillers necessarily have a BET surface of smaller than 50 m²/g(Schriftenreihe Pigmente Degussa Kieselsäuren [Publication SeriesPigments Degussa Silicas], number 12, page 5 as well as number 13, page3). Preferably the at least one non-reinforcing filler d₂) is asubstance selected from the group comprising alkaline earth oxides,alkaline earth hydroxides, alkaline earth fluoride, alkaline earthcarbonates, calcium apatite (Ca₅[(F,Cl,OH 1/2CO₃)|(PO₄)₃], especiallycalcium hydroxyapatite (Ca₅[(OH)|(PO₄)₃]), titanium dioxide, zirconiumoxide, aluminum hydroxide, silicon dioxide, precipitated silica andcalcium carbonate. Obviously the aforesaid compounds can be usedindividually or in any desired combinations with one another and, infact, both in hydrophilic and in hydrophobed form.

Preferably the non-reinforcing fillers d₂) used have an average particlesize of larger than 0.1 μm (Ullmann's Encyclopedia of IndustrialChemistry, Volume 21, page 523).

As an improvement of the inventive idea, it is proposed in formulationof the dental material as a two-component system that the at least onenon-reinforcing filler d₂) in base component A have a water content ofat most 0.5 wt %, particularly preferably at most 0.1 wt %, quiteparticularly preferably at most 0.05 wt % and, most preferably, beabsolutely or substantially anhydrous.

According to a special embodiment of the present invention, the at leastone non-reinforcing filler d₂) in base component A has a pH of 4 to 11,preferably of 5 to 9 and particularly preferably of 5.0 to 8.5.

Base component A of the inventive dental material preferably contains,relative to component A, 0 to 80 wt %, particularly preferably 0.05 to75 wt % and quite particularly preferably 0.1 to 70 wt %, and catalystcomponent B preferably contains, relative to component B, 0 to 80 wt %,particularly preferably 0.05 to 75 wt % and quite particularlypreferably 0.1 to 70 wt % of at least one non-reinforcing filler d₂).

In an improvement of the inventive idea, it is proposed that, informulation as a two-component material, the reinforcing and/ornon-reinforcing fillers contained in catalyst component B have a pH ofbetween 2.0 and 7.0 and quite particularly preferably such with a pH ofbetween 3.0 and 7.0.

On the whole, the total content of fillers, both in formulation of thedental material as a one-component and as a two-component system, is 0to 80 wt %, preferably 0.01 to 80 wt %, particularly preferably 0.1 to75 wt % and quite particularly preferably 0.2 to 70 wt % relative to thetotal mixture.

As alkoxysilyl-functional polyethers a) there can be used in principleall polyethers containing alkoxysilyl groups, and the polyether backbonecan be linear and/or branched and, for example, can be composed ofpolyethylene oxide, polypropylene oxide, polytetrahydrofuran and/orcopolymers thereof, while these monomers can be present statistically,in blocks or in a tactic arrangement. As starters for the polyethersand/or copolymers there can be used monohydric or polyhydric alcohols,such as methanol, butanol, glycerin, trimethylpropane, pentaerythritoland sorbitol. For example, copolymers of polytetrahydrofuran withpolyethylene oxide or of polyethylene oxide and polypropylene oxide canbe used, polypropylene oxide being particularly preferred. Furthermore,there are preferred polyethers with side alkyl groups, wherein every orat least every tenth monomeric structural unit has a side alkyl group.Suitable commercial products are Acclaim 4200, Acclaim 6320N, Acclaim12200, Acclaim 8200 and Acclaim 6300 of Bayer AG, Polyglycol P11/300 andPolyglycol P413000 (Clariant) as well as poly(ethyleneglycol-ran-propylene glycol) (Aldrich). Polyethers a) preferably have anumber-average molecular weight of 500 to 25,000 g/mol and particularlypreferably of 5,000 to 20,000 g/mol.

Besides the chain length (elasticity), the alkoxysilyl functionalization(curing kinetics) and the number of urethane/urea groups (viscosity,rheology), a selection criterion for polyethers that are suitableaccording to the invention is the hydrophilicity of the polyether, whichis determined via the number, structure and polarity of the monomericrepeating units of the polyether polymer. The hydrophilicity of a dentalimpression material must on the one hand be sufficiently high to ensuregood flow onto moist dental substance (low contact angle), but on theother hand the material must not be too hydrophilic, since otherwisewater, moisture or saliva leads to swelling during the taking of animpression or during disinfection or during production of a plastercast, and so the necessary dimensional accuracy is no longer assured.Beyond this, the hydrophilicity of the polyether is also responsible forthe solubility, among other properties, of the inventive catalyst.

According to a particular embodiment of the present invention, the atleast one alkoxysilyl-functional polyether has a content of polyethergroups of between 5 and 30 mmol/g and particularly preferably of between10 and 25 mmol/g.

Preferably the alkoxysilyl structural unit or the alkoxysilyl structuralunits of polyether a) is or are disposed in terminal position relativeto the polymer backbone and are given by the general formula I—SiR⁵R⁶R⁷

-   -   in which R⁵, R⁶ and R⁷ independently of one another are alkoxy,        alkyl, aryl, aralkyl, alkylaryl groups or hydrogen, preferably        butoxy, propoxy, ethoxy, methoxy, hexyl, pentyl, butyl, propyl,        ethyl or methyl groups, particularly preferably ethoxy, methoxy,        ethyl or methyl groups, with the proviso that at least one of        the aforesaid groups, preferably two or all three groups, are        alkoxy groups.

In an improvement of the inventive idea, it is proposed that the atleast one polyether a) have an alkoxy group content of 0.02 to 12mmol/g, particularly preferably of 0.04 to 6 and quite particularlypreferably of 0.04 to 3 mmol/g.

By means of the type and number of alkoxy groups per silicon atom, it ispossible to adjust the condensation kinetics and thus the processing andsetting times of the dental material. These parameters are preferablychosen in such a way that the processing time is 30 seconds to 3minutes, particularly preferably between 1 and 2.5 minutes and quiteparticularly preferably between 1.5 and 2 minutes and/or the settingtime in the patient's mouth (known as the mouth removal time),determined according to ISO 4823 (1992 edition), is at most 15 minutes,particularly preferably at most 10 minutes, quite particularlypreferably at most 7 minutes and most preferably 6 minutes.

The at least one polyether a) preferably contains, as a third structuralunit (besides the terminal alkoxy groups and the polyether groups),alkylene spacers, which are disposed on each of the terminal alkoxysilylgroups and which are preferably C₁ to C₆ alkyl groups, particularlypreferably C₁ to C₃ alkyl groups, quite particularly preferably ethylenegroups and/or methylene groups and most preferably methylene groups.

In addition, the at least one polyether a) can contain, as a fourthstructural unit, 0 to 8 mmol/g, particularly preferably 0 to 4 mmol/g,quite particularly preferably 0.02 to 2 mmol/g and most preferably 0.1to 0.4 mmol/g of urethane groups and/or 0 to 8 mmol/g, particularlypreferably 0 to 2 mmol/g, quite particularly preferably 0.02 to 2 mmol/gand most preferably 0.1 to 0.4 mmol/g of urea groups. Particularly whenthe at least one polyether a) contains urea and/or urethane groups asthe fourth structural unit, a methylene group is preferred as spacer. Bythe use of such α-activated alkoxysilyl polyethers there are obtainedhydrophilic, storage-stable two-component dental impression compounds,which become cross-linked surprisingly rapidly by condensation reactionwith a salt to be used according to the invention as catalyst. On thewhole, the content of urethane or urea groups per molecule should bekept as low as possible, in order to minimize intermolecularinteractions between the individual polyether chains, in order to keepthe viscosity caused by the polyether addition as low as possible, thuspermitting the addition of larger quantities of fillers in the dentalmaterial and in turn imparting more margin for formulation and achievingmore cost-effective recipes.

Within the scope of the present invention, it has proved advantageous touse polyethers that contain no urethane or urea groups within thepolyether chain and that have at each chain end at most/not more thanone urethane or urea group and at most/not more than one (alkoxy)silylgroup and at most/not more than one methylene spacer group. Comparedwith the polyurethane-alkoxysilyl polyethers used in the prior art, theuse of these polyethers leads to formulations with lower viscosity, sothat more fillers can be added to the dental materials, thus leading toa reduction of production costs.

According to a further particular embodiment of the present invention,the individual structural units of the at least one polyether a) arearranged as follows:

-   -   in which R¹, R² and R³ independently of one another are alkoxy,        alkyl, aryl, aralkyl, alkylaryl groups or hydrogen, preferably        butoxy, propoxy, ethoxy, methoxy, hexyl, pentyl, butyl, propyl,        ethyl or methyl groups, particularly preferably ethoxy, methoxy,        ethyl or methyl groups, with the proviso that at least one of        the aforesaid groups, preferably two or all three groups, are        alkoxy groups, as well as    -   x=1 to 6, preferably x=2 to 4 and quite particularly preferably        x=2, n=1 to 6, preferably n=1 to 3 and quite particularly        preferably n=1, as well as m=0 or 1, particularly preferably        m=1,    -   or    -   in which R¹, R² and R³ independently of one another are alkoxy,        alkyl, aryl, aralkyl, alkylaryl groups or hydrogen, preferably        butoxy, propoxy, ethoxy, methoxy, hexyl, pentyl, butyl, propyl,        ethyl or methyl groups, particularly preferably ethoxy, methoxy,        ethyl or methyl groups, with the proviso that at least one of        the aforesaid groups, preferably two or all three groups, are        alkoxy groups, as well as    -   x=1 to 6, preferably x=2 to 4 and quite particularly preferably        x=2, n=1 to 6, preferably n=1 to 3 and quite particularly        preferably n=1, as well as l=0 or 1, particularly preferably        l=1,        According to a further particular embodiment of the present        invention, the alkyl spacer in the aforesaid structural units is        methylene (n=1).

The synthesis of these alkoxysilyl-functional polyethers is known and isdescribed in, for example, German Patent 10104079 A1, European Patent0629819 B1, German Patent 10139132, U.S. Pat. No. 4,906,707, EuropeanPatent 0372561 A1, European Patent 1303560 A1 and European Patent0170865 B1, which are introduced here as reference and are valid as partof the disclosure. Examples of polyethers that are commerciallyavailable and suitable within the scope of the present invention are MSPolymer S 203H, MS Polymer S 303H (Kaneka), Polymer XP ST55, ST50, ST51,ST53 (Hanse), SLM 414000 (Wacker), SLM 414001 (Wacker), Baycoll XP 2458and Desmoseal XP 2447 (Bayer AG), thedimethoxy(methyl)silylmethyl-carbamate-terminated polyether:

sold under the trade name SLM 414000, and thedimethoxy(methyl)silylmethyl-urea-terminated polyether:

being particularly preferred.

In an improvement of the inventive idea, it is proposed that one or moreof the following additives or auxiliary agents be added to the inventivedental material:

-   -   f) thixotropic agent,    -   g) water scavenger,    -   h) paste-forming agent,    -   i) surfactant,    -   j) active agent,    -   k) plasticizer,    -   l) substance permitting optical scanning,    -   m) flavor and/or fragrance,    -   n) substance permitting diagnostics,    -   o) fluoridating agent,    -   p) bleaching agent,    -   q) desensitizing agent,    -   r) bond promoter,    -   s) dye,    -   t) indicator,    -   u) stabilizer (antioxidant, radical scavenger).

Thixotropic agent f) can be added optionally to the inventive dentalmaterial, and high molecular weight polyethers in particular, such aspolyethylene glycol, polyethylene glycol/polypropylene glycolcopolymers, polytetrahydrofuran, hydrocarbon waxes, amide waxes,triglycerides, silicas and silicates have proved particularly suitablefor this purpose.

According to a particular embodiment of the present invention, thedental materials, when formulated as a two-component system, preferablycontain in base component A at least one water scavenger g), whichparticularly preferably is selected from the group comprisingalkoxysilanes, titanates, such as tetraisopropyl titanate, zirconates,such as tetrapropyl zirconate, zeolites, aluminum sulfate, anhydrouscalcium sulfate (such as Drierite®), blue gel and/or oxazolidines.

In an improvement of the inventive idea, it is proposed that one or morefunctional alkoxysilanes be used as water scavenger g), since thecross-linking rate, the structure and the properties of the resultingelastomer can be additionally adjusted by such compounds. Preferably theat least one functional alkoxysilane is a compound of general formula IIR⁸ _(4-x)—Si—R⁹ _(x)

-   -   with R⁸=H, alkyl, alkenyl, —(CH₂)_(n)-Z, where n=1 to 6,    -   R⁹=alkoxy,    -   Z=NH₂, NHR, NR₂, where R=alkyl, aminoalkyl, —C(CO)OCH₃, as well        as x=1, 2, 3 or 4,    -   where particularly preferably R⁸=alkenyl, especially vinyl, or        —(CH₂)_(n)-Z with Z═NHR and n=1 or 3, particularly n=1, and/or        x=3 and/or R═—C(O)OCH₃.

Particularly preferably, the at least one functional alkoxysilane g) isvinyltrimethoxysilane, N-trimethoxysilylmethyl-O-methyl carbamate and/ora compound of the following formula:

-   -   in which n=1 to 6, preferably n=1 or 3, particularly preferably        n=1, d=0 or 1, and    -   R¹⁰=a linear or branched C₁ to C₃₀ alkyl group, in which some of        the hydrogen atoms may be substituted by halogen atoms, OH—,        NH₂—, NO₂— or even other C₁ to C₆ alkyl groups.

The aforesaid compounds are reactive silanes, which function as waterscavengers to eliminate any traces of water still present from componentA of the dental composition.

Furthermore, the inventive two-component dental materials preferablycontain, and particularly preferably, in fact, when formulated as atwo-component system, at least one paste-forming agent h) in catalystcomponent B, since this permits the adjustment of a paste-likeconsistency, for example of low viscosity, medium viscosity or highviscosity, as well as homogeneous mixing of the salt and of the solidreinforcing and non-reinforcing fillers. Preferably there is used as theat least one paste-forming agent h) a compound selected from the groupcomprising polyethers, polyvinylpyrrolidones, polyurethanes, polyesters,waxes, vaselines, paraffin oils, silicone oils, polyhydric alcohols,propylene glycols, polypropylene glycols, ethylene glycols, polyethyleneglycols, copolymers of N-vinylpyrrolidone and vinyl acetate,carboxymethyl-, methyl-, hydroxyethyl-, hydroxypropylcellulose,polysaccharides, glycerin and poly(meth)acrylic acids. Obviously theinventive dental materials may also contain any desired combination oftwo or more of the aforesaid compounds.

Particularly preferred are hydrophilic paste-forming agents, in whichthe inventive catalyst salt can be mixed homogeneously with water. Themiscibility can be further improved by addition of surfactants.Particularly preferred representatives are polyethers, polyurethanes,polyesters, polyhydric alcohols, particularly propylene glycols,polypropylene glycols, ethylene glycols, polyethylene glycols, butyleneglycols, polybutylene glycols and glycerin as well as mixtures andcopolymers thereof.

The compounds i) that may be used as surfactant, emulsifier and/orstabilizer are preferably anionic surfactants, particularly preferablyalkyl sulfates, alkylbenzenesulfonates or alkylbenzene phosphates,cationic surfactants, particularly preferably tetraalkylammoniumhalides, nonionic surfactants, particularly preferably alkyl andalkylphenyl polyalkylene oxides, fatty acid alkoxylates, fatty alcoholalkoxylates as well as alkyl ethers and alkyl esters thereof, fatty acidalkylolamides, sucrose fatty acid esters, trialkylamine oxides, siliconesurfactants (such as Silwet L77, Tegopren 5878) or fluorosurfactants, oramphoteric surfactants, particularly preferably sulfated or oxyethylatedcondensation products of alkenylphenols and formaldehyde, ethyleneoxide/propylene oxide block polymers or modified polysiloxanes.Advantageously there can also be used surfactants that can beincorporated by polymerization into the alkoxysilyl-functionalpolyethers a), as disclosed in U.S. Pat. No. 4,160,778, which isintroduced here as reference and is valid as part of the disclosure. Inaddition or as an alternative to this, there can also be usedderivatives of the aforesaid surfactants, for example such that havefunctional groups such as —OH, —CH═CH₂, —OCO—(CH₃)C═CH₂ as well asalkoxysilyl groups. In addition, other surfactants known to the personskilled in the art can be used, even if they are less preferred.

As the compounds i) used, there is preferably used a siliconesurfactant, since it has been shown in the scope of the presentinvention that very low contact angles, determined with the “sessiledrop” method can be surprisingly obtained in the polyether matrix.

These mixtures are characterized by excellent wettability andoutstanding ability to flow onto moist dental and tissue substance.Despite these good hydrophilic properties, the material does not swellon contact with aqueous media, such as water, saliva, blood,disinfectant solution or aqueous plaster slurry. The good initialwettability of the mixtures is important for obtaining a true-to-detailimpression with the impression material in the patient's mouth duringprocessing and initial contact with moist oral/dental substance, and ismanifested by a low contact angle of smaller than 50°, especiallysmaller than or equal to 45°, measured with a contact-angle measuringinstrument of the Kruss Co. at 20° C. using the “sessile drop”measurement method. In addition, the cured impression material is alsocharacterized at the time of production of a plaster cast (directly or 2hours after curing) by a contact angle of smaller than 60°, especiallysmaller than 55°.

In addition, the inventive dental materials can contain one or moreactive agents j), which, in formulation as a two-component system, canbe contained in base component A or in catalyst component B, dependingon their chemical functionality. The active agents to be used accordingto the invention include in particular astringents, such as epinephrine,antibacterial and/or antifungal substances, such as hexitidines (forexample, 5-amino-1,3-bis(2-ethylhexyl)-5-methylhexahydropyrimidine),triclosanes (for example, 2,4,4′-trichloro-2-hydroxydiphenyl ether) andchlorhexidine:

-   -   in which R¹, R² and R³ independently of one another are alkoxy,        alkyl, aryl, aralkyl, alkylaryl groups or hydrogen, preferably        butoxy, propoxy, ethoxy, methoxy, hexyl, pentyl, butyl, propyl,        ethyl or methyl groups, particularly preferably ethoxy, methoxy,        ethyl or methyl groups, with the proviso that at least one of        the aforesaid groups, preferably two or all three groups, are        alkoxy groups.

As plasticizers k) there can be used in particular non-reactivepolyethers, polyesters, polyurethanes, phthalates, mono-, di-, tri- orhigher esters, especially acetyl tributyl citrate, Mesamoll® (Bayer) andtriglycerides, which in formulation as a two-component system are addedto component A and/or to component B, depending on their chemicalnature.

As the compounds l) permitting optical readability/scanning there can beused all substances known for this purpose to the person skilled in theart, especially metal powder, metal pigments, metallic pigments, zincoxide, zirconium oxide and titanium dioxide, which in formulation as atwo-component system are added to component A and/or to component B,depending on their chemical nature.

In addition, the inventive dental materials can contain, in one of thetwo or in both components, standard flavors and/or fragrances m) and/oradditives n) that are useful for diagnostics, as described in, forexample, European Patent 1339373, International Patent PCT/EP00/05418and German Patent 10061195.

As fluoridating auxiliaries o), there have proved suitable in particularsodium fluoride, potassium fluoride, ammonium fluoride, fluorophosphatesand amine fluorides, such asN′-octadecylbimethylenediamine-N,N,N′-bis(2-ethanol) dihydrofluoride (asdescribed in ZM 93, Number 15, pages 32 et seq.), which in formulationas a two-component system can also be added to component A and/or tocomponent B, depending on their chemical nature.

In addition, the inventive dental material, in formulation as atwo-component system, can contain as bleaching agent p), in component Aand/or component B, one or more various peroxides, which are preferablyselected from the group comprising alkali metal and alkaline earthperoxides, hydrogen peroxide and carbamide peroxide.

Examples of suitable desensitization agents q) are potassium salts, suchas potassium nitrate, Nelkenol and Eugenol.

As bond promoters r), for example for developing a bond between theimpression material and an impression spoon of stainless steel and/orplastic, there are suitable in particular alkoxysilanes, epoxysilanes,aminosilanes and methacrylate silanes.

Examples of suitable dyes s) are dye pigments in the form of Al, Ca, Baoxides/lacquered dye, which in formulation as a two-component system canalso be added to component A and/or to component B, depending on theirchemical nature, just as the auxiliary agents described hereinabove,unless otherwise indicated.

Furthermore, dye indicators t), whose color changes as a function of thepH or on the basis of pH changes during mixing of components A and B orupon contact with water, can be added to the inventive dental materialin component A and/or component B in formulation as a two-componentsystem.

As stabilizers and/or antioxidants u) there can be used in the inventivetwo-component dental materials compounds selected in particular from thegroup comprising polymeric trimethyldihydroquinoline, diphenylderivatives, phenothiazine, phenyl-α-naphthylamine,4,4′-methylene-bis-2,6-di-tert-butylphenol, butylhydroxytoluene,butylhydroxyanisole (BHA) and methoxyphenol (hydroxyanisole). Examplesof such compounds are the products Irganoz 1010, 1076, 1036, MD 1024,Irgafos 168, 38, Irgacor 252 LD/252FC, 1405, 1930, 153, Tinuvin 328, P,384, 900, 928, 327, 1130, 400, 292, 144, 123, 622 and Chimassorb 119,which are commercially available from the Ciba-Geigy Co.

Preferably the inventive two-component dental material is stored insuitable primary packages, such as tubes, cans and particularlypreferably in cartridges and tubular bags, as described in, for exampleEuropean Patent 0723807 A2, European Patent A 0541972, InternationalPatent PCT/EP/980193, European Patent A 0492412, European Patent A0492413 and European Patent 0950908 A1, which are introduced herewith asreference and thus are valid as part of the disclosure, and has beenproportioned in a manner tailored to the subsequent use.

Further subject matter of the present invention is mixtures that can beobtained by mixing components A and B of the inventive two-componentdental material described hereinabove. Preferably base component A ismixed with catalyst component B in a ratio of 1:1 to 20:1, particularlypreferably of 1:1 to 10:1 and quite particularly preferably of 1:1, 2:1,4:1 or 5:1.

Hereinafter the invention will be explained on the basis of examplesthat demonstrate the inventive ideas but do not restrict them.

EXAMPLE 1 TO 6 (ACCORDING TO THE INVENTION)

(Production of Various Catalyst Components B with Different CatalystSalts of Strong Acids and Pyridine to be Used According to theInvention)

Production of Various Catalyst Components B

Various catalyst salts formed from the quantities of strong acids andpyridine indicated in Table 1 were dissolved in 2.9 parts ofdemineralized water (Ampuwa, pH 5.8). Then the individual salt solutionswere mixed for 5 minutes in a vacuum mixing beaker with 36 parts ofpolypropylene glycol with an average molecular weight of 4000 g/mol, 50parts of quartz flour with an average particle size of 7 μm and 6 partsof highly disperse, hydrophobed silica with a BET surface of 170 m²/g.Thereafter homogeneous mixing was continued for a further 30 minutesunder vacuum.

Medium viscosity materials (ISO 4823), representing the various catalystcomponents B of the inventive impression material on the basis ofalkoxysilyl polyethers, were obtained. The materials were filled intotubular bags (PE/Al/PE laminated film) and stored. They had pH values inthe range of pH 1 to pH 3.

Production of a Base Component A

40 parts of a polypropylene glycol, which was functionalized in terminalposition with dimethoxymethylsilyl groups via urethane groups and methylspacers, the functionalized polypropylene glycol having a viscosity of10,000 mPas at 20° C., was mixed for 5 minutes in a vacuum mixer underdry argon protective gas atmosphere with 50 parts of a driedcristobalite filler surface-modified with trimethylsilyl groups andhaving an average particle size of 7 μm, 7 parts of a dried, highlydisperse, pyrogenically prepared, hydrophobed silica with a BET surfaceof 170 m²/g, 0.8 parts of vinyltrimethoxysilane and 2 parts of siliconesurfactant. Thereafter homogeneous mixing was continued for a further 30minutes under vacuum.

A medium viscosity material (ISO 4823), representing base component A ofthe inventive impression material on the basis of alkoxysilylpolyethers, was obtained. The material was filled into tubular bags(PE/Al/PE laminated film) and stored.

Mixing of Catalyst Components B and Base Component A

By means of an electrical dispensing unit (Plug & Press System,Kettenbach GmbH & Co. KG), 1 part of each of the catalyst components Bdescribed hereinabove and 5 parts of base component A produced accordingto the above procedure were mixed homogeneously out of tubular bags viaa dynamic mixer.

The setting times of the dental materials based on alkoxysilylpolyethers and produced in this way are listed in Table 1, and furtherapplication-related properties for the dental material obtained inExample 2 are listed in Tables 3 and 4.

Examples 1 to 6 show that the inventive compositions surprisinglyexhibit curing kinetics that are excellent forcondensation-cross-linking systems. Quick-setting impression materialswith practical processing times can be obtained. The person skilled inthe art is aware that the setting time of the individual examples can beeasily adjusted to a desired value by increasing or decreasing thequantity of catalyst salt used.

As follows in particular from Table 4, for the compound obtained inExample 2, the inventive dental materials meet all requirements forfunctional dental impression material, especially as regards Shore Ahardness, recovery after deformation, consistency of the individualcomponents and of the mixture, linear changes of dimensions and contactangle. In particular, there are obtained values that are excellent forthe hydrophilicity, which is determined by measurement of contact angle.

COMPARISON EXAMPLE 1 (NOT ACCORDING TO THE INVENTION)

A salt formed from the quantities of pyridine and acetic acid indicatedin Table 1 was dissolved in 5.0 parts of demineralized water (Ampuwa, pH5.8) and processed to a catalyst component B in the same way as inExamples 1 to 6.

One part of the catalyst components B described hereinabove and 5 partsof base component A according to Example 1 were homogeneously mixed outof tubular bags by means of an electrical dispensing unit (Plug & PressSystem, Kettenbach GmbH & Co. KG) via a dynamic mixer (Kettenbach GmbH &Co. KG).

The setting time of the material based on alkoxysilyl polyether andprepared in this way is listed in Table 1.

As is evident from Table 1, the salt formed from pyridine and a weakacid with a pKs value of 4.76 (acetic acid) and used in ComparisonExample 1 has, in contrast to the inventive formulations, anunacceptable setting time of longer than 60 minutes.

EXAMPLES 7 TO 13 (ACCORDING TO THE INVENTION)

(Production of Various Catalyst Components B with Different CatalystSalts of Strong Acids and Weak Bases to be Used According to theInvention)

Production of Various Catalyst Components B

Various catalyst salts formed from the quantities of strong acids andweak bases indicated in Table 2 were dissolved in 2.9 parts ofdemineralized water (Ampuwa, pH 5.8). Then the individual salt solutionswere mixed for 5 minutes in a vacuum mixing beaker with 36 parts ofpolypropylene glycol with an average molecular weight of 4000 g/mol, 50parts of quartz flour with an average particle size of 7 μm and 6 partsof highly disperse, hydrophobed silica with a BET surface of 170 m²/g.Thereafter homogeneous mixing was continued for a further 30 minutesunder vacuum.

Medium viscosity materials (ISO 4823), representing the various catalystcomponents B of the inventive impression material on the basis ofalkoxysilyl polyethers, were obtained. The materials were filled intotubular bags (PE/Al/PE laminated film) and stored.

Mixing of Catalyst Components B and Base Component A from Example 1

By means of an electrical dispensing unit (Plug & Press System,Kettenbach GmbH & Co. KG), 1 part of each of the catalyst components Bdescribed hereinabove and 5 parts of base component A produced accordingto Example 1 were mixed homogeneously out of tubular bags via a dynamicmixer (Kettenbach GmbH & Co. KG).

The setting times of the dental materials based on alkoxysilylpolyethers and produced in this way are listed in Table 2.

Examples 7 to 13 show that the inventive compositions surprisinglyexhibit curing kinetics that are excellent forcondensation-cross-linking systems. Quick-setting impression materialswith practical processing times can be obtained. The person skilled inthe art is aware that the setting time of the individual examples can beeasily adjusted to a desired value by increasing or decreasing thequantity of catalyst salt used.

COMPARISON EXAMPLES 2 AND 3 (NOT ACCORDING TO THE INVENTION)

Two different salts formed from the quantities of p-toluenesulfonic acidand various bases indicated in Table 2 were dissolved in 5.0 parts ofdemineralized water (Ampuwa, pH 5.8) and processed to a catalystcomponent B in the same way as in Examples 1 to 6.

One part of each of the catalyst components B described hereinabove and5 parts of base component A according to Example 1 were homogeneouslymixed out of tubular bags by means of an electrical dispensing unit(Plug & Press System, Kettenbach GmbH & Co. KG) via a dynamic mixer(Kettenbach GmbH & Co. KG).

The setting times of the materials based on alkoxysilyl polyether andprepared in this way are listed in Table 2.

As is evident from Table 2, the materials used in the comparisonexamples and containing salts whose base component has a value outsidethe PK_(BH+) range of −1 to 7 specified according to the invention donot cure.

COMPARISON EXAMPLES 4 (NOT ACCORDING TO THE INVENTION)

(Acid-Catalyzed Condensation Cross-Linked Dental Material on the Basisof Alkoxysilyl Polyethers According to Examples 3 and 5 of EuropeanPatent 1226808 A2)

A prior art acid-catalyzed dental material based on alkoxysilylpolyethers and composed of an acid catalyst component B and a basecomponent A is prepared and mixed according to Examples 3 and 5 ofEuropean Patent 1226808 A2.

The processing time, setting time and setting time after a thermalstress test of one week at 60° C. of the composition prepared accordingto Comparison Example 4 are listed in Table 3, by comparison with thedental material based on alkoxysilyl polyethers and obtained accordingto the invention in Example 2.

Compared with the inventive dental material based on alkoxysilylpolyethers and obtained in Example 2, the acid catalyst system fromEuropean Patent 1226808 A2 (Examples 3 and 5) no longer exhibits curingafter storage in the thermal stress test (one week at 60° C.) This showsthat the catalyst component from Example 3 of European Patent 1226088 A2is unstable. This leads to lengthening of the setting time. However, asetting time that remains constant independently of storage time is oneof the most important requirements of a dental impression material.TABLE 1 Composition and setting time of the compounds according toExamples 1 to 6 and Comparison Example 1 Acid proportion Base proportionpKs value Inventive Examples/ [%] [%] of acid Comparison Examples Strongacids Weak base Content [mmol/g] Content [mmol/g] (H₂O) Setting timeExample 1 Benzenesulfonic acid Pyridine 1.46 0.73  0.7 ⁴⁾ 6′30″ (6.32)(12.64) Example 2 p-Toluenesulfonic acid Pyridine 1.58 0.73  0.7 ²⁾7′30″ (5.81) (12.64) Example 3 Trifluoromethanesulfonic Pyridine 1.380.73 −10 ³⁾ 8′00″ acid (6.66) (12.64) Example 4 4-Sulfophthalic acidPyridine 2.27 0.73  <0.7 11′00″  (4.06) (12.64) Example 5Trichloroacetic acid Pyridine 1.5 0.73  0.7 ⁴⁾ 12′00″  (6.12) (12.64)Example 6 Trifluoroacetic acid Pyridine 1.05 0.73  −0.25 ²⁾ 13′00″ (8.77) (12.64) Comparison Example 1 Acetic acid Pyridine 1.29 0.73  4.76⁴⁾  >60′00″    (4.06) (12.64)²⁾ Source: http://www.cem.msu.edu/˜reusch/VirtualText/suppmnt2.htm³⁾ Source: http://www.tgs-chemie.de/pks-werte.htm⁴⁾ Source: http://www.zirchrom.com/organic.htm, “Dissociation constantsof organic acids and bases”

TABLE 2 Composition and setting time of the compounds according toExamples 7 to 13 and Comparison Examples 2 and 3 Acid Base proportionproportion pKS [%] [%] value of Inventive Examples/ Content Content acidSetting Comparison Examples Strong acids Weak base [mmol/g] [mmol/g](H₂O) time Example 7 p-Toluenesulfonic acid Pyrrole 0.19 0.49 0.0 ²⁾ <30 s (14.91) (5.81) Example 8 p-Toluenesulfonic acid2,4-Dimethylpyrrole 0.88 1.58 2.55 ³⁾ <30 s (10.51) (5.81) Example 9p-Toluenesulfonic acid 2,5-Dimethylpyrrole 0.88 1.58 −0.71 ³⁾  <30 s(10.51) (5.81) Example 10 p-Toluenesulfonic acid N,N-Dimethylaniline1.11 1.58 5.15 ⁴⁾ <1′00″  (8.25) (5.81) Example 11Trifluoromethanesulfonic N,N-2,4,6-Pentamethylaniline 0.47 0.43 5.15 ⁵⁾4′00″ acid (6.13) (6.66) Example 12 p-Toluenesulfonic acidN,N-2,4,6-Pentamethylaniline 0.47 1.58 5.15 ⁵⁾ 6′00″ (6.13) (5.81)Example 13 p-Toluenesulfonic acid Pyridine 0.73 1.58 5.25 ⁴⁾ 8′30″(12.64) (5.81) Comparison Example 2 p-Toluenesulfonic acid 1,4- 0.320.49 8.8 ²⁾  no Diazabicyclo[2.2.2]octene (8.91) (5.81) reactionComparison Example 3 p-Toluenesulfonic acid Triethanolamine 0.43 0.497.77 ⁴⁾ no (6.70) (5.81) reaction²⁾ Source: http://www.cem.msu.edu/˜reusch/VirtualText/suppmnt2.htm³⁾ Source: Y. Chiang, E. B. Whipple, J. Am. Chem. Soc., 1963, Vol. 85,2763⁴⁾ Source: http://www.zirchrom.com/organic.htm, “Dissociation constantsof organic acids and bases”⁵⁾ In 50% alcohol. Source: W. C. Davies, H. W. Addis, J. Chem. Soc.,1937, 1622

TABLE 3 Processing times, setting times and stabilities of impressionmaterials on the basis of alkoxysilyl polyethers by comparison withExamples 3 and 5 of European Patent 1226808 A2 Stability: Setting timeImpression after one week material: Processing time ¹⁾ Setting time ⁴⁾at 60° C. ³⁾ Example 2 3.00 minutes 7.50 minutes  7.75 minutesComparison 0.50 minutes 5.00 minutes >15.00 minutes Example 4 (Examples3 and 5 of European Patent 1226808 A2)¹⁾ According to ISO 4823²⁾ The setting time was determined by recovery after deformation inaccordance with ISO 4823 (1992 Edition)³⁾ Storage in sealed tubular bags of PE/A1/PE laminated film, see under²⁾ for measurement

TABLE 4 Application-related properties of the compositions according toExample 2 Example 2 Catalyst salt of p-toluenesulfonic acid withpyridine Consistency ¹⁾ 30 Catalyst component B Consistency ¹⁾ 33 Basecomponent A Consistency of the mixture ²⁾ 36 Linear dimensional change³⁾ −0.60% Shore A hardness immediately after end of 30 setting ⁴⁾ ShoreA hardness immediately after 15 hours of 60 storage ⁴⁾ Contact angle ⁵⁾30°/40° Recovery after deformation ⁶⁾ 98.05%¹⁾ On the basis of ISO 4823, consistency of the mixture, loading weight500 g, loading time 15 seconds²⁾ According to ISO 4823, consistency of the mixture, loading weight1500 g, loading time 5 seconds³⁾ According to ISO 4823⁴⁾ According to DIN 53505 with Zwick Co. digital Shore hardness tester⁵⁾ Measured according to the sessile drop method, G40 contact-anglemeasuring system of the Krüss Co., initial contact angle (age ofspecimen tested: application of the drop 45 seconds after the start ofmixing), measurement time: 30 seconds after application of the drop. Useof demineralized water.⁶⁾ According to ISO 4823

1. A condensation-cross-linking dental material, especially dentalimpression material, containing: a) at least one alkoxysilyl-functionalpolyether and b) at least one catalyst, wherein the at least onecatalyst b) is a salt formed from a weak organic base whose PK_(BH+)value measured in water is between −1 and 7 and at least one strong acidwhose pKs value measured in water is lower than
 2. 2. Acondensation-cross-linking two-component dental material, especiallydental impression material, with a component A containing: a) at leastone alkoxysilyl-functional polyether and a component B containing b) atleast one catalyst and c) water, wherein the at least one catalyst b) isa salt formed from a weak organic base whose pK_(BH+) value measured inwater is between −1 and 7 and at least one strong acid whose pKs valuemeasured in water is lower than
 2. 3. A condensation-cross-linkingdental material according to claim 1, wherein the at least one catalystb) is a salt formed from a weak organic base whose pK_(BH+) valuemeasured in water is between −1 and 7 and at least one strong acid whosepKs value measured in water is lower than 2, the acid having a structurethat permits mesomeric stabilization of the negative charge afterdeprotonation of the acid.
 4. A condensation-cross-linking dentalmaterial according to claim 1, further comprising at least onereinforcing filler d₁) with a BET surface of at least 50 m²/g and/or atleast one non-reinforcing filler d₂) with a BET surface of smaller than50 m²/g.
 5. A dental material according to claim 1, wherein the at leastone catalyst salt used is formed from at least one base whose PK_(BH+)value measured in water is between 1 and 7, particularly preferablybetween 2 and 6 and quite particularly preferably between 3 and 6 and/orat least one acid whose pKs value measured in water is smaller than 1and particularly preferably smaller than or equal to 0.7.
 6. A dentalmaterial according to claim 1, wherein the at least one catalyst is asalt formed from an acid chosen from the group comprisingp-toluenesulfonic acid, fluorosulfonic acid, trifluoromethanesulfonicacid, fluorosulfuric acid, 4-sulfophthalic acid, trichloroacetic acid,trifluoroacetic acid, benzenesulfonic acid and combinations thereofand/or from a base selected from the group comprising pyrrolederivatives, dimethylaniline, pyridine, 2,4,6-N,N-pentamethylaniline,N,N-dimethylaniline, phenetedine, acridine, phenanthridine, quinoline,isoquinoline, 2-amino-4,6-dimethylpyrazine, 4,6-dimethylpyridinamine,3-methylpyridine (3-picoline), 4-phenylpyridine, 4-vinylpyridine,pyridazine, 2-ethylpyridine, 2-butylpyridine, 1,7-phenanthroline,2-aminopyrimidine, 2-isopropylpyridine, 2-vinylpyridine,2-N,N-dimethylaminopyridine, quinazoline, 4-chloropyridine, phenazine,4-acetylpyridine, methyl nicotinate, 3-benzoylpyridine, 2,2′-bipyridine,2-phenylpyridine, 2-tert-butylpyridine, pyrimidine, 3-iodopyridine,3-fluoropyridine, 3-chloropyridine, 3-bromopyridine, pyrazine,7,8-benzoquinoline, 2-chloropyridine, 4-cyanopyridine and combinationsthereof.
 7. A dental material according to claim 1, further comprising,relative to the total mixture, 0.0005 to 0.5 mmol/g, particularlypreferably 0.0005 to 0.25 mmol/g and quite particularly preferably0.0005 to 0.05 mmol/g of catalyst salt.
 8. A dental material accordingto claim 1, wherein the at least one catalyst salt in the polyethermatrix, preferably a polyether matrix comprising as structural unitpolytetrahydrofuran, polyethylene glycol and particularly preferablypolypropylene glycol as well as mixtures and copolymers thereof, hassufficiently high solubility that, when used in a quantity of 0.0005 to0.5 mmol/g relative to the total mixture, it achieves curing of thedental material, determined by recovery after deformation according toISO 4823 (1992 edition), in less than or equal to 30 minutes,particularly preferably less than or equal to 15 minutes for aduplicating compound and in less than or equal to 15 minutes,particularly preferably less than or equal to 10 minutes, quiteparticularly preferably less than or equal to 7 minutes and mostpreferably less than or equal to 6 minutes for a dental impressioncompound.
 9. A dental material according to claim 1, wherein, besidesthe one or more salts according to claim 1, the dental material containsno further catalyst, especially no metalloorganic compounds, heavy metalcarboxylate salts, tertiary amines and free acids.
 10. A dental materialaccording to claim 1, wherein the at least one alkoxysilyl-functionalpolyether a) contains, as a third structural unit, alkylene spacers,which are disposed on each of the terminal alkoxysilyl groups and whichare particularly preferably C₁ to C₆ alkyl groups, quite particularlypreferably C₁ to C₃ alkyl groups and most particularly preferablyethylene groups (C₂) and/or methylene groups (C₁) and, as a fourthstructural unit, 0 to 8 mmol/g, particularly preferably 0 to 4 mmol/g,quite particularly preferably 0.02 to 2 mmol/g and most preferably 0.1to 0.4 mmol/g of urethane groups and/or 0 to 8 mmol/g, particularlypreferably 0 to 2 mmol/g, quite particularly preferably 0.02 to 2 mmol/gand most preferably 0.1 to 0.4 mmol/g of urea groups, wherein thealkoxysilyl polyethers that are most preferred are those that contain nourethane or urea groups within the polyether chain and that have at eachchain end at most one or not more than one urethane and/or urea groupand at most one or not more than one methylene spacer group, theindividual structural units of the at least one polyether a) preferablybeing arranged according to

in which R¹, R² and R³ independently of one another are alkoxy, alkyl,aryl, aralkyl, alkylaryl groups or hydrogen, preferably butoxy, propoxy,ethoxy, methoxy, hexyl, pentyl, butyl, propyl, ethyl or methyl groups,particularly preferably ethoxy, methoxy, ethyl or methyl groups, withthe proviso that at least one of the aforesaid groups, preferably two orall three groups, are alkoxy groups, as well as x=1 to 6, preferably x2to 4 and quite particularly preferably x=2, n=1 to 6, preferably n=1 to3 and quite particularly preferably n=1, as well as m=0 or 1,particularly preferably m=1, and/or

in which R¹, R² and R³ independently of one another are alkoxy, alkyl,aryl, aralkyl, alkylaryl groups or hydrogen, preferably butoxy, propoxy,ethoxy, methoxy, hexyl, pentyl, butyl, propyl, ethyl or methyl groups,particularly preferably ethoxy, methoxy, ethyl or methyl groups, withthe proviso that at least one of the aforesaid groups, preferably two orall three groups, are alkoxy groups, as well as x=1 to 6, preferably x=2to 4 and quite particularly preferably x=2, n=1 to 6, preferably n=1 to3 and quite particularly preferably n=1, as well as l=0 or 1,particularly preferably l=1.
 11. A dental material according to claim10, wherein n is equal to
 1. 12. A dental material according to claim 1,wherein the at least one polyether a) contains a structural unitselected from the group comprising polytetrahydrofuran, polyethyleneglycol, polypropylene glycol, copolymers thereof and mixtures thereof.13. A dental material according to claim 1, further comprising at leastone paste-forming agent h), which is preferably selected from the groupcomprising polyethers, polyvinylpyrrolidones, polyurethanes, polyesters,waxes, vaselines, paraffin oils, silicone oils, polyhydric alcohols,propylene glycols, polypropylene glycols, ethylene glycols, polyethyleneglycols, copolymers of N-vinylpyrrolidone and vinyl acetate,carboxymethyl-, methyl-, hydroxyethyl-, hydroxypropylcellulose,polysaccharides and poly(meth)acrylic acids.
 14. A dental materialaccording to claim 1, further comprising at least one water scavengerg), which preferably is vinyltrimethoxysilane,N-trimethoxysilylmethyl-O-methyl carbamate and/or a compound of thefollowing formula:

in which n=1 to 6, preferably n=1 or 3, particularly preferably n=1, d=0or 1, and R¹⁰=a linear or branched C₁ to C₃₀ alkyl group, in which someof the hydrogen atoms may be substituted by halogen atoms, OH—, NH₂—,NO₂— or even other C₁ to C₆ alkyl groups.
 15. A mixture that can beobtained by mixing components A and B of the two-component dentalmaterial according to claim 2, wherein the base component A is mixedwith the catalyst component B in a ratio of 1:1 to 20:1, particularlypreferably of 1:1 to 10:1 and quite particularly preferably of 1:1, 2:1,4:1 or 5:1.
 16. The use of a dental material according to claim 1 indental medicine or dentistry.